 $(function(){
	  var show_num = [];
	  draw(show_num);
	  $("#canvas").on('click',function(){
	   draw(show_num);
	  })
	  $(".btn").on('click',function(){
	   var val = $(".input-val").val().toLowerCase();
	   var num = show_num.join("");
	   if(val==''){
	    alert('请输入验证码！');
	   }else if(val == num){
	    alert('提交成功！');
	    $(".input-val").val('');
	    // draw(show_num);
	   }else{
	    alert('验证码错误！请重新输入！');
	    $(".input-val").val('');
	    // draw(show_num);
	   }
	  })
	 })
	 //生成并渲染出验证码图形
	 function draw(show_num) {
	  var canvas_width=$('#canvas').width();
	  var canvas_height=$('#canvas').height();
	  var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
	  var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
	  canvas.width = canvas_width;
	  canvas.height = canvas_height;
	  var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
	  var aCode = sCode.split(",");
	  var aLength = aCode.length;//获取到数组的长度
	  for (var i = 0; i < 4; i++) { //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
	   var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
	   // var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
	   var deg = Math.random() - 0.5; //产生一个随机弧度
	   var txt = aCode[j];//得到随机的一个内容
	   show_num[i] = txt.toLowerCase();
	   var x = 10 + i * 20;//文字在canvas上的x坐标
	   var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
	   context.font = "bold 23px 微软雅黑";
	   context.translate(x, y);
	   context.rotate(deg);
	   context.fillStyle = randomColor();
	   context.fillText(txt, 0, 0);
	   context.rotate(-deg);
	   context.translate(-x, -y);
	  }
	  for (var i = 0; i <= 5; i++) { //验证码上显示线条
	   context.strokeStyle = randomColor();
	   context.beginPath();
	   context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
	   context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
	   context.stroke();
	  }
	  for (var i = 0; i <= 30; i++) { //验证码上显示小点
	   context.strokeStyle = randomColor();
	   context.beginPath();
	   var x = Math.random() * canvas_width;
	   var y = Math.random() * canvas_height;
	   context.moveTo(x, y);
	   context.lineTo(x + 1, y + 1);
	   context.stroke();
	  }
	 }
	 //得到随机的颜色值
	 function randomColor() {
	  var r = Math.floor(Math.random() * 256);
	  var g = Math.floor(Math.random() * 256);
	  var b = Math.floor(Math.random() * 256);
	  return "rgb(" + r + "," + g + "," + b + ")";
	 }